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my brains - let me show you them (Photo credit: Liz Henry)

An experimental tool designed to “peek” into a patient’s brain and find signs of consciousness could eventually give doctors a way to more accurately judge chances of recovery from serious brain trauma – and in the process change the nature of end-of-life decisions.

Today, doctors don’t have many methods available to gauge the consciousness of a patient unable to respond verbally or in other subtle ways in response to simple questions--such as blinking an eye, squeezing a hand, or raising a finger. In these cases, typically when a patient has suffered a severe brain injury, there’s ample guesswork that goes into determining whether consciousness is still lingering under the surface.

The best clinical method available to get closer to an answer involves placing the patient in an MRI machine and scanning the brain while telling the patient to envision an action like throwing a ball or running through a field. By tracking activity patterns in the patient’s brain, it’s theoretically possible to tell if the person is able to unconsciously acknowledge and process the request. If it appears that the patient’s brain can respond even though the patient can’t verbalize the response, the person is said to suffer from “locked-in syndrome”.

The problem with this method is that it’s far from clear what the brain activity is actually revealing about consciousness. Significant brain activity is possible even in a vegetative state, and isn’t necessarily a clue that recovery is possible.

Since consciousness is spread across multiple brain regions, it’s possible for one part of the brain to respond while others are entirely unresponsive. One way to think about this is the starter on a damaged car engine still working even though gas can’t reach the engine; a minimal “signal” from the starter is produced by turning the key, even though the engine can’t run.

The new tool, developed by researchers from Italy’s University of Milan, could provide doctors with a more objective method that gauges the complexity of a patient’s consciousness. The tool combines three steps: first a magnetic pulse is sent through a coil into the brain designed to “wake it up,” and then an EEG machine measures brain wave activity produced by neurons firing in response to the pulse. Finally, the activity is measured via a formula that puts a finer point on the nature of the patient's consciousness.

That final step is the secret ingredient that makes this tool different: instead of simply trying to identify brain activity (something MRI machines can already do) it produces a measure of the complexity of consciousness--what the researchers call the perturbational complexity index (PCI). "Consciousness can grow and shrink," said Dr. Marcello Massimini, a neurophysiologist who led the research, in an AP report about the experimental tool. By figuring out the level of “growing” or “shrinking”, doctors can more objectively gauge whether a patient is exhibiting an adequate level of consciousness to recover.

According to the AP report, the research team compared tests from 32 healthy people who were awake, asleep, dreaming or anesthetized, and 20 people with a variety of serious brain injuries. “The two patients with locked-in syndrome clearly were aware, scoring nearly as high as awake and healthy people,” they reported. “The patients diagnosed as being in a vegetative state had scores as low as people rendered unconscious by the most powerful anesthesia. The minimally conscious were somewhere in-between.”

The researchers emphasize that the tool is far from becoming a bedside medical option, but the research opens the door to measuring levels of consciousness that correlate with recovery from serious brain injury. This knowledge could potentially change the way end-of-life decisions are made by providing doctors and loved ones with a firmer means to evaluate whether a patient has the capacity to recover.

On the other hand, the same decisions could become all the more agonizing by knowing that even a minimal level of consciousness persists—not enough to spark full recovery, but enough to say that the patient’s brain is still functioning, albeit marginally.